1. Technical Field
The present invention relates to a view angle control sheet which is suitably used for display devices such as an organic light emitting diode (hereinafter referred to as an “OLED”) display and a liquid crystal display (hereinafter referred to as an “LCD”).
2. Background Art
Usually it is preferable that an OLED display, an LCD, and the like have a wide view angle such that a good image is obtained when an observer sees the image from any position. For example, Patent Document 1 discloses a light diffusion sheet, in which plural unit lenses are formed in a one-dimensional direction or a two-dimensional direction, the unit lens includes a total reflection portion where total reflection of a part of an incident light beam is generated in an inner plane of the total reflection portion, the unit lens is made of a material having a predetermined refractive index N1, and a portion located between the adjacent unit lenses is filled with a material having a predetermined refractive index N2.
On the other hand, for example, when a person performs work in a commuter train, sometimes the person needs to prevent other people from taking a look inside a screen. In such cases, it is desirable that the view angle be controlled such that the screen can be seen only from the observer of the display while the screen cannot be seen from other people. In order to meet such the demand, for example, a louver type view angle control sheet is developed and used as shown in FIG. 15.
Patent Document 1: Japanese Patent Application Laid-Open No. 2003-50307